Ablation catheters and systems including rotational monitoring means

ABSTRACT

The present disclosure provides an improved ablation catheter. In particular, the present disclosure provides an improved renal denervation ablation catheter and system including a catheter handle and a means for tracking, monitoring, and/or recording the circumferential angular history of the renal denervation ablation catheter handle. The renal denervation ablation catheters in accordance with the present disclosure are well-suited for use with a renal denervation ablation system that can record the circumferential angular history of the renal denervation catheter handle, and hence the circumferential angular ablation history of the catheter electrode within a vessel, and use this data in combination with other known information to estimate the percent circumferential denervation of the vessel.

BACKGROUND OF THE DISCLOSURE

a. Field of the Disclosure

The present disclosure generally relates to ablation catheters. Inparticular, the present disclosure relates to renal denervation ablationcatheters and systems including a catheter handle and a means fortracking, recording, and/or monitoring the circumferential angularhistory of the renal denervation ablation catheter handle. The renaldenervation ablation catheters in accordance with the present disclosureare well-suited for use with a renal denervation ablation system thatcan track and record the circumferential angular history of the renaldenervation catheter handle, and hence the circumferential angularablation history of the catheter electrode(s) within a vessel, and usethis data in combination with other known information to estimate thepercent circumferential denervation of the vessel.

b. Background Art

It is known that various ablation procedures for the ablation ofperivascular renal nerves have been used for the treatment ofhypertension, and specifically for drug-resistant hypertension.Generally, one or more radiofrequency electrodes are introduced into thebody and fed into the renal artery and used to ablate the efferent andafferent nerves that generally run the length of the artery. In somecases, a single ablation procedure may include six to ten or moreablation areas along and around the wall of the artery. Typically, thedoctor performing the procedure will ablate one discreet area of theartery and then pull the ablation electrode a desired distancelengthwise about the length of the artery and also rotate the handle ofthe catheter to move the ablation electrode circumferentially around theartery. In some cases, the doctor may move the ablation electrodecircumferentially about 45 degrees around the artery wall betweenablations. By varying the ablation treatment sites lengthwise down andcircumferentially around the artery wall, the overall damage to the wallcan be reduced or minimized while the overall ablation of the efferentand afferent nerves can still be substantially complete and effective.

During the ablation procedure, the doctor performing the proceduregenerally attempts to monitor and track all of the areas of the arterywall that have previously been ablated to avoid over-treatment of anyone site. This monitoring and tracking should be done both along thelength of the artery as well as around the circumference of the arterywall to ensure proper ablation of the arterial nerves and the bestprocedural results.

Based on the foregoing, it would be advantageous to provide acircumferential angle tracking device for tracking and recording therotational history of a renal denervation catheter handle, and hence arenal denervation catheter electrode(s) directed thereby, to allow formore precise and thorough ablation of a renal artery and a reducedoccurrence of artery damage due to over-ablation of a single spot.Additionally, it would be beneficial if the circumferential angletracking device is easily integratable with both single andmultiple-electrode ablation catheter systems.

SUMMARY OF THE DISCLOSURE

It is desirable to be able to provide a means for tracking, monitoring,and/or recording the rotational history of an ablation catheter handle,and specifically a renal denervation ablation catheter handle, and hencethe ablation electrode(s) directed thereby, to allow for a more completecircumferential artery ablation and improved procedural outcomes. It isalso desirable to provide methods of using the means for tracking,monitoring, and/or recording the rotational ablation history of anablation catheter and methods of estimating the overall percentdenervation of renal efferent and afferent nerves. The presentdisclosure is directed to various means for tracking, monitoring, and/orrecording the rotational history of an ablation catheter handle, andspecifically a renal ablation catheter handle such that thecircumferential angle is recorded for each ablation made by theelectrode so that a more complete and accurate total ablation proceduremay be performed. The embodiments disclosed herein are applicable toboth single-electrode and multiple-electrode ablation systems. Thepresent disclosure is also directed to methods of tracking, monitoring,and/or recording the angular circumferential ablation history of anablation catheter, and to methods of estimating the circumferentialpercent renal denervation for a renal artery.

The present disclosure is directed to an ablation catheter systemcomprising a catheter handle, an elongate catheter body, an electrode,and a means for tracking a circumferential rotational history of thecatheter handle.

The present disclosure is further directed to a method for tracking thecircumferential ablation history of a renal artery. The method comprisesablating at least two areas on the renal artery using an ablation systemcomprising an ablation catheter comprising a catheter handle, anelongate catheter body, an electrode, and a means for tracking acircumferential rotational history of the catheter handle, and recordingthe circumferential rotational history of the catheter handle for eachablation.

The present disclosure is further directed to a method for estimatingthe circumferential percent renal denervation for a renal artery. Themethod comprises performing at least two ablations on the renal arteryusing an ablation system comprising an ablation catheter comprising acatheter handle, an elongate catheter body, an electrode, and a meansfor recording a circumferential rotational history of the catheterhandle, recording a circumferential angle for each ablation, and usingan average ablation spot size, a diameter of the artery, andcircumferential angle for each ablation to estimate the circumferentialpercent renal denervation for the artery.

It has been found that the rotational angular ablation history of anablation electrode, and specifically a renal ablation electrode, can betracked, monitored and/or recorded precisely by using a rotationalmonitoring device in combination with the catheter handle that directsthe ablation electrode inside of the artery. By monitoring, trackingand/or recording the rotational history of the catheter handle thatdirects or “steers” the ablation electrode within the artery, theablation history of the electrode can be precisely tracked and recordedallowing for the percent denervation of the artery to be estimated andmonitored during the renal denervation procedure. By more closelymonitoring and controlling the ablation history of the ablationelectrode, a more precise and thorough ablation of the nerves in therenal artery can be accomplished resulting in improved patient outcomes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a steerable ablation catheter.

FIG. 2 shows a steerable ablation catheter including rotationalmonitoring means in accordance with one embodiment of the presentdisclosure.

FIG. 3 shows a steerable ablation catheter including rotationalmonitoring means in accordance with another embodiment of the presentdisclosure.

FIG. 4 shows a steerable ablation catheter including rotationalmonitoring means in accordance with yet another embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The ablation catheters, and specifically the renal denervation ablationscatheters, and related methods of the present disclosure provide animproved ablation catheter that can easily and accurately track, record,and/or monitor the angular rotational history of the catheter, andspecifically the catheter handle, during an ablation procedure, such asa renal denervation ablation procedure. This angular rotational historyis directly related to the rotational ablation history of the catheterelectrode located within the body such that an operator of the cathetersystem can accurately track and determine the circumferential ablationhistory of an artery or other area being treated. With thiscircumferential ablation history, the operator can more readilyascertain whether a complete circumferential ablation of an artery hasbeen made, and can also use this circumferential ablation history alongwith other known information to accurately estimate the percent ofdenervation of renal efferent and afferent nerves. This can lead toimproved patient outcomes and improved safety.

Embodiments of the present disclosure provide specific improvements toan ablation catheter, and specifically to an ablation catheter for usein a renal denervation procedure. The ablation catheters of the presentdisclosure include a means for tracking a circumferential rotationalhistory of the catheter handle such that the circumferential rotationalhistory of the ablation electrode directed by the catheter handle withinan artery is accurately known. The rotational monitoring means fortracking the circumferential history of the catheter handle may includea non-rotating rotational monitor (relative to the catheter handle)appropriately marked with angular measurements and configured such thatthe catheter handle may rotate within, or may include electronic orother means for rotational monitoring as described herein.

Referring now to FIG. 1, there is illustrated steerable ablationcatheter 2 for ablating target tissue of a vessel of the body inaccordance with one embodiment of the present disclosure. Althoughgenerally described herein in the context of a renal denervationcatheter for the ablation of nerves in a vessel wall, steerable ablationcatheter 2 may be any suitable ablation catheter conventionally knownthat may benefit from the rotational monitoring means as describedherein. Steerable ablation catheter 2 includes catheter handle 10 andflexible elongate catheter body 4 having proximal end 6 and distal end8. The length of steerable ablation catheter 2 is generally sufficientto access a target vessel of the body, such as a patient's renal artery,relative to a percutaneous access location. Steerable ablation catheter2 also includes hub 12 operably connected to an inner lumen (not shown)within catheter handle 10 for insertion or delivery of catheterassemblies and wires as conventionally known. Steerable ablationcatheter 2 further includes electrode 14 near distal end 8. Electrode 14may be a single electrode, or may contain multiple electrodes as isknown in the art. Catheter handle 10 is coupled to flexible elongatecatheter body 4 such that a torque imparted to catheter handle 10 can betransmitted to flexible elongate catheter body 4, as well as toelectrode 14 that is coupled to flexible elongate catheter body 4.

Referring now to FIG. 2, there is illustrated a first embodiment of thepresent disclosure wherein steerable ablation catheter 2 includesflexible elongate catheter body 4, catheter handle 10, and non-rotatingrotational monitor 16 including angular markings 18, 20, 22, 24, 26, 28,29, and 50 for tracking the rotational history of catheter handle 10.Catheter handle 10 further includes rotational angle indicator 32.Non-rotating rotational monitor 16 is mounted to catheter handle 10 suchthat when catheter handle 10 is rotated during an ablation procedure,catheter handle 10, including rotational angle indicator 32 easilyrotates such that electrode 14 directed thereby rotates as well, butnon-rotating rotational monitor 16 remains in a fixed, non-moveableposition, such that rotational angle indicator 32 can be rotated aroundnon-rotating rotational monitor 16 and its position noted by angularmarkings 18, 20, 22, 24, 26, 28, 29, and 50. This allows for precisetracking of the rotational history of catheter handle 10, and henceelectrode 14 directed thereby, during an ablation procedure.

As noted above, during a renal denervation procedure a doctor willgenerally ablate multiple segments along and around the artery wall forseveral seconds to treat the efferent and afferent nerves that typicallyrun the length of the artery. Treating the entire circumferential areaof the artery is desirable and, as such, the doctor will typicallyrotate catheter handle 10 prior to each successive ablation treatment tomove electrode 14 circumferentially around the interior of the artery.By including rotational angle indicator 32 on catheter handle 10 ofsteerable ablation catheter 2, a doctor can easily and accuratelydetermine where, around the circumference of the artery, electrode 14has traveled and provided ablation such that a more complete andthorough circumferential ablation of the artery can be accomplishedduring the procedure. For example, prior to any ablation, a doctor mayset the rotational angle indicator 32 to the 0 degree angular marking 18position, and then after a first ablation is made on a renal artery, thedoctor may pull electrode 14 along the length of the artery a desiredamount and then rotate catheter handle 10 45 degrees until rotationalangle indicator 32 shows 45 degrees before a second ablation is done todirect electrode 14 a known amount about the circumference of the arterywall. After the second ablation, the doctor may again pull electrode 14along the length of the artery a desired amount and then rotate catheterhandle 10 another 45 degrees until rotational angle indictor 32 shows 90degrees before a third ablation is done. This process may be usedsuccessively throughout the entire ablation procedure to improve thecircumferential ablation history of the procedure. As will be recognizedby one of skill in the art, the actual amount of rotation of electrode14 about the circumference of a vessel wall prior to each ablation maybe more or less than 45 degrees without departing from the scope of thepresent disclosure. Also, each successive amount of rotation ofelectrode 14 about the circumference of a vessel may be the same ordifferent.

In one specific embodiment using non-rotating rotational monitor 16 asdescribed above, non-rotating rotational monitor 16 is wired orotherwise connected through steerable ablation catheter 2, such that thereadings from non-rotating rotational monitor 16 may be transmitted to avisual medium for a doctor to monitor during a procedure. In thisspecific embodiment, as catheter handle 10 of steerable ablationcatheter 2 is rotated during the procedure, the angle of rotation is notonly visible on non-rotating rotational monitor 16 using rotationalangle indicator 32 as described above, but may also be electronicallytransmitted to a suitable screen for visualization there as well. Thesystem may also be appropriately configured for audible indications aswell.

Referring now to FIG. 3, there is illustrated steerable ablationcatheter 2 for ablating target tissue of a vessel of the body inaccordance with another embodiment of the present disclosure. Steerableablation catheter 2 includes catheter handle 10 and flexible elongatecatheter body 4 having proximal end 6 and distal end 8. The length ofsteerable ablation catheter 2 is generally sufficient to access a targetvessel of the body, such as a patient's renal artery, relative to apercutaneous access location. Steerable ablation catheter 2 alsoincludes hub 12 operably connected to an inner lumen (not shown) withincatheter handle 10 for insertion or delivery of catheter assemblies andwires. Steerable ablation catheter 2 further includes electrode 14 neardistal end 8. Electrode 14 may be a single electrode, or may containmultiple electrodes as is known in the art. Catheter handle 10 iscoupled to flexible elongate catheter body 4 such that a torque impartedto catheter handle 10 can be transmitted to flexible elongate catheterbody 4, as well as to electrode 14 that is coupled to flexible elongatecatheter body 4. Catheter handle 10 additionally includesmicroelectromechanical systems (MEMS) sensor 30, such as a MEMS sensorchip, which may include analog and/or digital technology for gatheringand transmitting data. In one embodiment, the MEMS sensor chip includesa MEMS inertial sensor chip suitable for tracking, recording, andtransmitting data related to rotational movement about an axis. SuchMEMS inertial sensor chips are known to those of skill in the art.

MEMS sensor 30 is suitably configured and installed onto or nearcatheter handle 10 to electronically track, record, and transmit therotational history of catheter handle 10 throughout an ablationprocedure such that the rotational history of electrode 14 may also beknown. MEMS sensor 30 may suitably be electronically connected and wiredthrough steerable ablation catheter 2 (or may be connected wirelessly)such that the readings from MEMS sensor 30 may be transmitted to avisual medium for a doctor to monitor during a procedure. In thisspecific embodiment, as catheter handle 10 of steerable ablationcatheter 2 is rotated during the procedure, the angle of rotation iselectronically tracked, recorded, and transmitted to a suitable screenfor visualization by the doctor such that the doctor can more accuratelyknow the ablation history of electrode 14 in the body, and specificallyin the artery. The system may also be appropriately configured foraudible indications as well.

Referring now to FIG. 4, there is illustrated an ablation cathetersystem including steerable ablation catheter 2 for ablating targettissue of a vessel of the body in accordance with yet another embodimentof the present disclosure. Steerable ablation catheter 2 includescatheter handle 10 and flexible elongate catheter body 4 having proximalend 6 and distal end 8. The length of steerable ablation catheter 2 isgenerally sufficient to access a target vessel of the body, such as apatient's renal artery, relative to a percutaneous access location.Steerable ablation catheter 2 also includes hub 12 operably connected toan inner lumen (not shown) within catheter handle 10 for insertion ordelivery of catheter assemblies and wires. Steerable ablation catheter 2further includes electrode 14 near distal end 8. Electrode 14 may be asingle electrode, or may contain multiple electrodes as is known in theart. Catheter handle 10 is coupled to flexible elongate catheter body 4such that a torque imparted to catheter handle 10 can be transmitted toflexible elongate catheter body 4, as well as electrode 14 that iscoupled to flexible elongate catheter body 4. The system additionallyincludes external motion detector 31 that is positioned to monitor,record, and transmit the rotational movement of catheter handle 10during an ablation procedure. External motion detector 31 may be ananalog motion detector or a digital motion detector. Suitable analog anddigital motion detectors are known to those of skill in the art.

External motion detector 31 is suitably configured in conjunction withcatheter handle 10 to electronically track, record, and transmit therotational history of catheter handle 10 throughout an ablationprocedure such that the rotational history of electrode 14 may also beknown. External motion detector 31 may suitably be electronicallyconnected such that the readings from external motion detector 31 aretransmitted to a visual medium for a doctor to monitor during aprocedure. In this specific embodiment, as catheter handle 10 ofsteerable ablation catheter 2 is rotated during the procedure, the angleof rotation is electronically tracked, recorded, and transmitted to asuitable screen for visualization by the doctor such that the doctor canmore accurately know that ablation history of electrode 14 in the body,and specifically in the artery. The system may also be appropriatelyconfigured for audible indications as well. Although illustrated hereinas an external motion detector, the present disclosure also contemplatesa motion detected coupled directly to the steerable ablation catheter,and specifically on the catheter handle of the steerable ablationcatheter.

The means for monitoring the rotational history of catheter handle 10 asset forth herein and specifically including non-rotating rotationalmonitor 16, MEMS sensor 30, and external motion detector 31, shoulddesirably have an output proportional to the actual rotation angle ofelectrode 14 directed by catheter handle 10; that is, although the meansfor monitoring as described herein is monitoring the rotational historyof catheter handle 10, the rotational angle output should be forelectrode 14 as directed by catheter handle 10. As such, if thetorque-ability of catheter handle 10 and electrode 14 is 1:1, theresulting rotational angle should so indicate and would be exactly thatof catheter handle 10. If the torque-ability is other than 1:1, therotational angle indicated should be appropriately calibrated tocompensate for the difference to ensure accurate measurements of thecircumferential ablation history.

In accordance with the present disclosure, the circumferentialrotational history of catheter handle 10, and hence the circumferentialablation history of electrode 14 directed by catheter handle 10 and usedto ablate the tissue, can be suitably used by a doctor not only tomonitor the circumferential ablation history for an artery or other bodyarea, but can also be used in combination with other information togenerate a percent overall circumferential denervation of the of theartery. This can be done in real time during the ablation procedure,which is advantageous as the accuracy and completeness of the procedurecan be improved as well as overall patient outcomes.

As noted herein, the present disclosure provides ablation catheters andsystems, as well as methods of their use, for recording the rotationalhistory of catheter handle 10, and hence the rotational ablation historyof electrode 14 attached to and directed by catheter handle 10 andlocated within a vessel in the body. This information, along withknowledge of the average ablation spot size and the diameter of thevessel being ablated, may provide acute procedural success informationto the doctor as to the overall percent denervation of the renalefferent and afferent nerves of the vessel.

For renal denervation procedures, the average ablation spot size on thevessel has a length of about 2 millimeters to about 5 millimeters, whichcorresponds generally to an area of about 3 square millimeters to about20 square millimeters. The average diameter of the vessel is generallyabout 2 millimeters to about 12 millimeters, including from about 3millimeters to about 10 millimeters, and including about 4 millimetersto about 8 millimeters. If a doctor knows the diameter of a vessel(D_(v)), the circumference of the vessel (C_(v)) can be calculated. Byknowing the average diameter of ablation spots (D_(as)) (with respect tothe circumference of the vessel), and the number of ablation spots(desirably at least 2, 3, 4, 5, 6, or more), the percent circumferentialdenervation of the vessel can be estimated using the following equation:% Circumferential Denervation=100×[[(D _(as1) +D _(as2) +D _(as3)+ . . .)−(O _(ca))]/C _(v)]wherein O_(ca) is the overlap of circumferential ablation as obtainedfrom the rotational monitor means as described herein. This equationestimates the percent circumferential denervation while accounting forany circumferential overlap of the ablation spots, which is determinedby the output of the rotational monitor means.

By allowing a doctor to have an estimation of the percentcircumferential denervation of a vessel as calculated in real timeduring a procedure, the present disclosure allows a doctor to makenecessary adjustments during a procedure to improve overall patientoutcomes and improves the probability of achieving the desired percentdenervation in a single procedure.

Although a number embodiments of this disclosure have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of the disclosure. For example, animportant feature of this disclosure is the rotational monitoring meansused in combination with the catheter handle that directs the ablationelectrode(s). One skilled in the art may modify the exact nature of therotational monitoring means without departing from the spirit or scopeof the disclosure. It is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be interpretedas illustrative only and not limiting. Changes in detail or structuremay be made without departing from the spirit of the disclosure asdefined in the claims.

What is claimed is:
 1. An ablation catheter system comprising a catheterhandle, an elongate catheter body, an electrode, and a means fortracking an angular rotational history of the catheter handle during anablation procedure, wherein the means for tracking an angular rotationalhistory of the catheter handle during an ablation procedure isconfigured to record a circumferential angle for each ablation made bythe electrode.
 2. The ablation catheter of claim 1 wherein the means fortracking an angular rotational history of the catheter handle is anon-rotating rotational monitor attached to and circumscribing thecatheter handle.
 3. The ablation catheter of claim 2 wherein thenon-rotating rotational monitor has an output proportional to arotational angle of the catheter handle.
 4. The ablation catheter ofclaim 2 wherein the non-rotating rotational monitor includes a series ofvisible markings indicating values for angles.
 5. The ablation catheterof claim 1 wherein the means for tracking an angular rotational historyof the catheter handle is an electronic means.
 6. The ablation catheterof claim 5 wherein the electronic means includes a motion detector. 7.The ablation catheter of claim 6 wherein the motion detector is externalto the ablation catheter.
 8. The ablation catheter of claim 5 whereinthe electronic means includes a micro-electromechanical system.
 9. Theablation catheter of claim 8 wherein the micro-electromechanical systemis external to the ablation catheter.
 10. The ablation catheter of claim1 wherein the ablation catheter is a single-electrode ablation catheter.11. The ablation catheter of claim 1 wherein the ablation catheter is amulti-electrode ablation catheter.
 12. A method for tracking thecircumferential ablation history of a renal artery, the methodcomprising: ablating at least two areas on the renal artery using anablation system comprising an ablation catheter comprising a catheterhandle, an elongate catheter body, and an electrode, the ablation systemfurther comprising a means for tracking an angular rotational history ofthe catheter handle during an ablation procedure, wherein the means fortracking an angular rotational history of the catheter handle isconfigured to record the circumferential angular ablation history of theelectrode within the renal artery; and recording a circumferential anglefor each ablation made by the electrode.
 13. The method of claim 12wherein the ablation system further includes a means for projecting therecorded circumferential angle for each ablation onto a visual medium.14. The method of claim 12 wherein the means for tracking an angularrotational history of the catheter handle is a non-rotating rotationalmonitor attached to the catheter handle.
 15. The method of claim 14wherein the non-rotating rotational monitor has an output proportionalto a rotational angle of the catheter handle.
 16. The method of claim 15wherein the non-rotating rotational monitor includes a series ofmarkings indicating values for angles.
 17. The method of claim 12wherein the means for tracking an angular rotational history of thecatheter handle is an electronic means.
 18. The method of claim 17wherein the electronic means includes a motion detector.
 19. The methodof claim 18 wherein the motion detector is external to the ablationcatheter.
 20. A method for estimating the circumferential percent renaldenervation for a renal artery, the method comprising: performing atleast two ablations on the renal artery using an ablation systemcomprising an ablation catheter comprising a catheter handle, anelongate catheter body, and an electrode, the ablation system furthercomprising a means for recording a circumferential rotational history ofthe catheter handle; recording a circumferential angle for eachablation; and using an average ablation spot size, a diameter of theartery, and circumferential angle for each ablation to estimate thecircumferential percent renal denervation for the artery.